Reading phone/online messages: YES - Always maintain authority to check on young teens
Opening posted mail: For minors yes - might be illegal when older
Going though their living area: HELL to the YES. Parents who don't do this don't love their kids
Keeping tabs on where they spend time, who with etc: I have to know the parents of anyone my kids visit regularly or goes out with.
Monitoring what monies are spent on: Plastic Only - Paper money? Naw.
“… the greatest detractor from high performance is fear: fear that you are not prepared, fear that you are in over your head, fear that you are not worthy, and ultimately, fear of failure. If you can eliminate that fear—not through arrogance or just wishing difficulties away, but through hard work and preparation—you will put yourself in an incredibly powerful position to take on the challenges you face" - Pete Carroll.